Análise comparativa entre diferentes revestimentos inibidores de corrosão em um aço microligado

Abstract

The highest rates of corrosion of metals are present in coastal regions due to sea air, in which there are droplets that move through the air and have high concentrations of sodium chloride (NaCl). This chemical compound is directly responsible for causing the oxidation of metals through oxygen and the metallic surface, resulting from the formation of a salt bridge. The annual cost due to corrosion can reach around 3% of GDP in industrialized countries. In these contexts, there is a need for constant research for cost reduction and for a greater use of materials, where ways to reduce this effect are revealed, such as the application of corrosion inhibitors. The process consists of coating the surfaces of materials resulting in the formation of protective films, which can be effective for multiple types of wear. The present study seeks to evaluate the effectiveness of three basic models of coatings found on the market, for application in a high-strength, low-alloy microalloyed steel, commonly used in shipbuilding. For this purpose, an immersion test in a saline bath was carried out for eight samples, which were separated into three pairs with different coating models and a totally neutral pair. The test for the corrosion analysis was carried out using the saline bath method, in which all samples were submerged in a mixture based on water and sodium chloride (5%), with a stipulated test time of 3 days and 7 days. Steel ASTM 131 AH36 was selected for the study, in which they were subjected to three different coatings, namely Spray Paint, Cold Galvanizing and Primer Pu + Spray Paint, using as reference a pair of samples without coatings. The results obtained showed a significant increase in corrosion resistance due to the inhibitors, and consequently, in the useful life of the metal. There was a positive achievement in combating corrosion for all applied coatings, with considerable reductions of up to 3 times for Cold Galvanizing and up to 15 times for Primer Pu + Spray Paint.